UNITED STATES PUBLIC HEALTH SERVICE 

RUPERT BLUE, Surgeon General 



DRIED MILK POWDER 



A REVIEW OF BRITISH EXPERIENCE 



REPRINT No. 473 

FROM THE 

PUBLIC HEALTH REPORTS 

June 28, 1918 
(Pages 1052-1055) 



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WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1918 



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OCT 23 1918 



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^ DRIED MILK POWDER. 

A REVIEW OF BRITISH EXPERIENCE. i 

The local Government board of Great Britain has recently issued a 
series of reports under the general classification '^Food Reports 
No. 24" upon the preparation, composition, and nutritive values of 
dried milk powders, with special reference to their use in infant 
feeding. It is stated that tliis article is coming into rather large use 
in the preparation of certain foodstuffs and in the feeding of infants. 
In view of these facts and of certain claims which have been made 
as to the advantages of this product over ordinary cow's milk, 
especially from the point of view of freedom from bacteria of a 
dangerous sort, a somewhat extensive inquiry into the entire sub- 
ject has been deemed advisable. 

History, Manufacture, and Uses. 

The first branch of this inquiry related to the use of dried milk 
in infant feeding and was carried out by Dr. F. J. H. Coutts with the 
assistance of Prof. Delepine. A brief history of dried milk and of 
its methods of preparation is first given. It is stated that as early 
as 1868 "desiccated milk" was an article of commerce. Since that 
time, and especially during the past 20 years, considerable advance 
has been made in the methods of preparation, the general purpose 
being to secure a dry residue by evaporation at the lowest possible 
temperature and in the shortest time. Most of the processes 
employed use one or another form of revolving heated drum, upon 
the surface of which a thin milk layer is spread and from wliich the 
dried product is scraped. The most recent processes inject a stream of 
partially condensed milk into a heated chamber in the form of a 
fine spray, the evaporation taking place in the air and the dry 
powder falling to the floor. In the factories the conditions of manu- 
facture, as regards general cleanliness, were found to be excellent. 
The author, however, does not agree with the conunonly expressed 
view of the desirability of small-scale manufacture upon the farm. 
He found in many such cases that the most elementary precautions 
as to cleanliness were being neglected. The importance of placing 
this industry under the supervision and control of public health 
officials is emphasized. About 5,000,000 pounds of milk powder 
were imported into England during 1915 of which one-half came 

1 Reprint from the Tublic Health Reports, vol. 33, No. 26, .Tune 28, 1918. pp. 1052-1055. 
72765°— 18 3 



4 DEIED MILK POWDER. 

from the United States, and the importance of some form of guarantee 
as to the conditions of manufacture of imported products is also 
noted. 

Tlie market product is of three main varieties, namely, full-cream, 
half cream, and skimmed. Certain firms, however, make other 
preparations, including some with additional cream. Certain prepa- 
rations also contain added cane sugar. 

Dried milk is used as a basis of certain proprietary infant foods. 
It is also employed in admixture with cocoa and sugar, with egg 
powder and sugar as a custard powder, and in various other combi- 
nations. Dried milk is said to be used extensively in many of the 
industries, particularly in the baking and confectionery trades. 
Reference is also made to a so-called synthetic dried milk m.ad« 
entirely from vegetable materials. The use of the word milk in this 
comiection is considered rather unfortunate. The ethics of labeling 
and advertisement are discussed, and the investigations showed oa 
the whole a reasonable regard to accuracy, although in some instances 
advertisements were decidedly objectionable. 

Physical and Chemical Characteristics. 

The literature on the physical and chemical characteristics of 
milk powders is quoted at length. Dr. Monier-Williams reported 
in 1909 upon a sample of whole milk powder, dried upon a drum at 
100° + , C. Upon mixing with a small amount of water, stirring until 
homogeneous, and then adding cold, previously boiled, distilled water 
to make a 12.5 per cent solution, a product was obtained which did 
not have the homogeneous appearance of fresh milk. It had a 
slight smell of boiled milk and the fat separated quickly as a yellow 
layer at the surface. The curd produced by rennet was flocculent 
and finely divided; that produced by acetic acid was shnilar to that 
produced from normal milk. The reconstituted milk did not con- 
tain the active enzymes of fresh milk as shown by the peroxydase 
reaction. The fat globules viewed under the microscope were in 
most cases larger than those in fresh milk and there was observed a 
considerable amount of undissolved proteid. A considerable pro- 
portion of the lactalbumen had been converted into a form insoluble 
in magnesium sulphate. The milk sugar had undergone no altera- 
tion. A somewhat extensive compilation of various analyses of 
milk powders is given. Among the foreign substances found are 
cane sugar, bicarbonate of soda, various preservatives, coloring 
matter, starch, foreign fat, dirt, and traces of certain metals. 

Bacteriology. 

A similar comprehensive review of the literature of the bacteriology 
of dried milk is given. In view of the small amount of information 



DRIED MILK POWDER. 5 

available, a further investigation was made by the author and 42 
samples of commercial preparations were submitted to the Lister 
Institute. Ten per cent solutions of the powder showed aerobic 
bacteria grr)wing at 22° C, ranging in numbers from 100 to 757,000 per 
cc. and at 37° C, from 100 to 892,000 per cc. ' The residts for tlio most 
part, however, ranged under 10,000 per cc. in each case. The 
presence of streptococci, enteriditis, and B. coli was recorded in many 
of the samples. There was no evidence of tuberculosis in guinea 
pigs inoculated from these samples. 

Investigations made at the factory indicated an enormous reduction 
in bacteria during the process of drying and a subsecpient recon- 
tamination during handling and packing. The experiment was 
tried of running through the drying process a specimen of milk from 
a tubercular cow and one heavily inoculated with a potato culture of 
tubercle bacilli. Subsequent inoculations of guinea pigs indicated 
that living tubercle bacilli may survive the process of manufacture of 
dried milk, but "th.Q course of the disease produced by the bacteria 
was very much slower than that of the disease produced in guinea 
pigs inoculated with the same amount of untreated tubercular 
milk." No evidence of tubercular infection was obtained by feeding 
experiments upon four young rabbits. 

Infant Feeding. 

Upon the basis of a review of the experience of man;;' authorities 
and of information obtained by personal visits to several large infant 
feedings stations, the opinion is expressed that when breast feeding 
is impossible dried milk is a very valuable food for infant feeding. 
This statement applies, however, only to milk of recent manufacture, 
made from a good quality of cow's milk imder hygienic conditions, 
iris probably no better than and perhaps slightly inferior to fresh 
cow's milk, but under the present conditions in cities, and especially 
in hot weather, it is often desirable to use it in preference to the latter, 
and this can be safely done without fear of prejudicing the health and 
progress of the infant. Many infants suffering from digestive 
troubles show excellent progress on dried milk. Scurvy and rickets 
are rare in infants fed on tliis preparation, although the occasional 
use of fruit juice is desirable. 

Increasingly large quantities of milk powder are being used in mater- 
nity and child welfare stations supported by public health authorities 
and voluntaiy agencies in England and Wales. A list is given of some 
75 districts, including some of the principal cities of Great Britain, in 
which this is the case. At Leicester a dried-milk depot is open every 
day and consultations are held twice each week. The milk powder is 
supplied in packages with directions and in three grades, namely, fuU 
cream, three-quarters cream, and half cream. The very poor obtain 



6 DRIED MILK POWDEE. 

this material at less than cost or even free, while the average pur- 
chaser pays a slight margin of profit. Similar details of the opera- 
tion of some of the other large weKare stations are given. 

For administrative purposes, under the "Sale of food and drugs 
act," milk powders are classed with condensed milk. An extensive 
bibliography closes the section. 

Nutritive Value. 

This section is a report of the investigation conducted by George 
Winfield, M. A., on behalf of the medical research committee. The 
conclusions are based in part upon observations at infant welfare 
centers in Leeds and Sheffield and in part on animal feeding experi- 
ments. The growth curves of children fed exclusively upon dried milk 
from birth closely Tesemble the average growth curve of breast-fed 
cliildren, although at somewhat lower levels by reason of the more 
delicate condition of these children. The conclusion is reached ' ' that 
cow's milk, during the process of desiccation, loses none of the 
characters which are necessary for the support of normal growth in 
infants." Teething and walking begin at normal ages, and there is 
no greater liability of rickets and scurvy. The experiments on rats 
led to the conclusion that dried milk as a sole food maintains an 
animal in good health and permits normal growth for periods which 
long outlast those corresponding with infancy and early childhood in 
the human subject. 

Examination of Milk Powders. 

This section of the report, prepared by Sir James Dobbie, Govern- 
ment chemist, presents in detail the methods of chemical examination 
employed and the analytical results obtained upon a large number of 
commercial samples of all sorts. These results are summarized in 
Dr. Coutts's report. 

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